1. Field of the Invention
This invention generally relates to the field of touch control technology and, more particularly, to a portable optical touch system, a portable optical touch device and a method for detecting a position of at least one object.
2. Description of the Related Art
FIG. 1 shows a solid diagram of a conventional optical touch system. Please refer to FIG. 1, an optical touch system 100 includes a panel 104, image sensing modules 106 and 108, a processing circuit 110, a reflecting element 112, a reflecting element 114 and a reflecting element 116. In addition, a quadrilateral area referred by a numerical reference 118 shown in FIG. 1 is served as a touch region of the optical touch system 100, and the image sensing modules 106 and 108 are respectively disposed at two different corners of the touch region 118 such that field of views of the two image sensing modules 106 and 108 can respectively cover the touch region 118. In this embodiment, a shape of the touch region 118 is a quadrilateral, and preferably a rectangle. A numerical reference 102 shown in FIG. 1 refers to an object.
In the components of the optical touch system 100, the reflecting element 112, reflecting element 114 and reflecting element 116 are made of retro-reflective material and configured to reflect incident light (e.g. IR light) to the touch region 118. The image sensing modules 106 and 108 are configured to acquire images looking across the touch region 118. The processing circuit 110 is configured to receive the images acquired by the image sensing modules 106 and 108, and calculate coordinates of the object 102 relative to the touch region 118 according to the images acquired by the image sensing modules 106 and 108.
FIG. 2 shows an operation diagram of the single point control of the optical touch system shown in FIG. 1. In FIG. 2, numerical references identical to those shown in FIG. 1 refer to the same components. As shown in FIG. 2, the image sensing module 106 detects the object 102 following a route 202 while the image sensing module 108 detects the object 102 following a route 204. Accordingly, as long as the processing circuit 110 is able to obtain linear equations of the routes 202, 204 and further to calculate a cross point thereof, a coordinate of the object 102 can then be obtained.
The method of how the two linear equations of the routes 202 and 204 are obtained by the optical touch system 100 will be illustrated hereinafter. But the structure of the image sensing modules 106 and 108 will be illustrated first.
Taking the optical sensing module 106 as an example, its structure is shown in FIG. 3. FIG. 3 shows a block diagram of the image sensing module 106. Please refer to FIG. 3, the image sensing module 106 includes an IR emitter 302, an optical lens set 304, an IR filter 306 allowing only IR light to pass through, and an image sensor 308; wherein the IR emitter 302 is configured to emit IR light to illuminate the touch region 118, reflecting element 112, reflecting element 114 and reflecting element 116; and the image sensor 308 acquires images inside and looking across the touch region 118 sequentially through the IR filter 306 and the optical lens set 304, and transmits the acquired images to the processing circuit 110. When the object 102 is inside the touch region 118, the image sensing module 106 is able to acquire images containing the image of the object 102 as shown in FIG. 4.
FIG. 4 shows a schematic diagram of an image acquired by the image sensing module 106. In FIG. 4, a white region referred by a numerical reference 402 is a bright zone which has a higher brightness in the acquired image and is formed by sensing the IR light emitted from the IR emitter 302 and the IR light reflected by the reflecting elements 114 and 116, and the bright zone 402 is served as a main sense region of the system. A numerical reference 404 refers to a dark zone formed by the object 102 from blocking the bright zone 402.
From FIGS. 2 and 4, it is known that as long as the processing circuit 110 is able to obtain an angle α (i.e. an included angle between the route 202 and an upper side of the touch region 118) and a gravity center (or a center) of the dark zone 404, the linear equation of the route 202 can then be calculated. Similarly, the processing circuit 110 is able to calculate the linear equation of the route 204 by using similar method. A coordinate of the object 102 is the cross point of the routes 202 and 204.
The optical touch system shown in FIG. 1 can perform the functions of a user input interface, e.g. a mouse, a keyboard or a touchpad for a computer system such that a user may perform input operation directly with his or her finger. However, since the optical touch system 100 has to adopt the physical panel 104, reflecting element 112, reflecting element 114 and reflecting element 116 for operation, the operational environment is significantly limited. Furthermore, the physical panel 104, reflecting element 112, reflecting element 114 and reflecting element 116 are not cheap such that this kind of optical touch system has a high price. In addition, as the panel 104 has a considerable volume and the reflecting element 112, reflecting element 114 and reflecting element 116 have considerable lengths, the size of the optical touch system 100 can not be further reduced to be carried easily.
Accordingly, problems need to be solved in a modern optical touch system 100 include the using environment, cost, size and portability.